what's eating you

appetite comes with eating

Starting an activity increases one's desire to continue it.

get what's coming to one

To experience the consequences of one's actions.

what's cooking

A greeting, similar to how are you?; what's happening?; what's up?; what's new?

what's eating

What is wrong with...? What is the problem with... (somebody)? Inquired regarding somebody who seems upset, worried, angry, etc.

what's going on

An informal greeting.

what's in it for me

What are the advantages of (something) to me, personally?

what's new

The latest developments in a particular situation or a person's life.

what's the beef

Why are you complaining? What are you complaining about?